A spat over the flag fluttering over a local government building might sound trivial. But in Northern Ireland, the decision to stop permanently flying the British flag outside Belfast City Hall has sparked some of the worst violence since the 1998 Good Friday peace deal.

Dozens of officers have been injured in attacks on police lines by furious protesters who, night after night, have thrown stones, bottles, fireworks, and, sometimes, Molotov cocktails -- violence that police say is orchestrated by the Ulster Volunteer Force, a pro-British paramilitary group.

Gunshots were heard Saturday, although police said later it appeared that blank rounds had been used. Monday night saw a mix of peaceful protest and riots during which police used water canon and fired plastic bullets, ITV News reported.

Peter Muhly / AFP - Getty Images

Loyalist protesters confront police as they gather at Belfast City Hall during a city council meeting Monday evening.

According to one pro-British politician, the demonstrators are staging a “revolution with a small r” against attempts by Irish nationalist parties to “remove their Britishness.”

Irish nationalists say they wanted to stop flying the flag from outside city hall because it is also used by pro-British paramilitaries and others to mark out their territory in the divided city and “intimidate” Catholics.

The Good Friday Agreement was credited with largely ending three decades of sectarian violence known as "The Troubles," during which British troops were sent in to patrol the streets and at least 3,600 people were killed.

It created an elected Northern Ireland assembly and devolved government in which power is shared between all sides, with traditional arch-enemies remarkably sitting side by side. The assembly meets in an imposing historic building, Stormont, over which the British flag flies for just 15 pre-agreed days each year. The recent violence was sparked by a vote that agreed a similar policy at local government level in Belfast last month.

"I don't think anyone should underestimate the threat it poses to long-term peace and security in Northern Ireland," she told NBC News.

"If people continue with violence, if it continues to escalate, if paramilitary involvement in that violence continues to grow, there's a real risk that we lose the progress we've made," Long said.

In the month since Belfast City Council in Northern Ireland voted to limit the numbers of days the Union flag flies over its City Hall, 62 police officers have been injured, tens of thousands of dollars' worth of damage caused and senior loyalist paramilitaries have been involved in orchestrating the violence. Channel Four Alex Thomson Channel Four Europe reports.

Long described the violence as a "reality check." While politics had delivered the peace process, she said, true reconciliation between the divided communities had been "left to one side because it's painful and difficult."

"What we have had is a papering over of the cracks," she said. "We have deep divisions, deep hatred and sectarianism and it won't go away by itself."

Long, a member of the U.K. parliament, said she and other politicians had received death threats after the Alliance Party members on Belfast City Council voted for an attempted compromise deal over the flag on Dec. 3.

It allowed the British flag to be flown on a number of designated days -- about 17 or 18 depending on the year -- rather than all the time or not at all.

An angry mob tried to storm the council chamber on the night of the vote and protests have continued sporadically since, with Monday seeing the fifth straight night of violence as the council met for the first time since last month’s controversial vote.

Police said Monday afternoon in an emailed statement that 96 people had been arrested since the latest unrest broke out and 61 police officers had been injured.

Billy Hutchinson, leader of the Progressive Unionist Party, which he said provides political advice to the UVF, told NBC News that the flag decision had “driven people mad.”

“I think what this is about is ordinary citizens who feel people are trying to remove their Britishness,” he said.

“You need to remember that this is the United Kingdom and the flag of the country is the union flag,” he added. “It would be a bit like if people wanted to take down the Stars and Stripes from some local government in the U.S.”

Paul Mcerlane / EPA

Local shoppers waiting for a bus watch as riot police follow pro-British protesters away from Belfast's City Hall during a protest Saturday.

Hutchinson said this was one of a number of actions by Sinn Fein that were “outside the spirit of the Good Friday Agreement.”

“I think the flag issue is a very big issue, I think it was the straw that broke the camel’s back … the catalyst that brought people onto the streets,” he said.

“I think it is serious, I think people need to recognize this is a revolution with a small ‘r.’ We cannot sustain this sort of inequality coming from Sinn Fein, who are disguising it as equality. They cannot force this through,” he said.

“I think if you listen to what the protesters are doing and saying, I think it is a threat [to the peace process]. It’s not a threat of armed violence… it’s a threat of community and political action,” he added.

Hutchinson stressed he believed in peaceful protest, and would seek to persude any UVF members taking part in violence to stop.

Jim McVeigh, leader of Sinn Fein’s councilors on Belfast City Council, said they had thought it would be better to have no national flags at city hall, but had agreed to the compromise deal, which was passed with votes from the nationalist Social Democratic and Labour Party, and the non-aligned Alliance Party.

“The issue of the flag and allegiance and identity is a very important one here in Belfast. [In the city] you will see flags are used to mark out territory … to intimidate,” he told NBC News, highlighting murals painted on walls and national colors on curbs.

Cathal Mcnaughton / Reuters

A burnt out car blocks Dee Street in east Belfast Sunday near a mural that supports the Ulster Volunteer Force paramilitary group.

McVeigh, who said he has had death threats since the vote, said he had expected some protests after the decision on Dec. 3, but added no one anticipated it would be “as ferocious as it has been.”

“The bottom line is we made the right decision. We’re not going to change that decision. The flag is not going to go back up [permanently]. These protests are futile,” he said.

A spokesman for the police trade union in Northern Ireland, who asked not to be named, told NBC News that the police were “severely stretched” in dealing with the riots and also the threat from dissident Irish nationalist groups.